Effectiveness distribution measurements for a row of heated circular jets impinging on a cylindrical convex surface at different inclinations

The spatially resolved effectiveness distributions for a single jet and row of circular jets impinging on a convex surface are reported in the present study. The impinging surface was inclined at 0°, 15°, 30° and 45° to the jet axis. Studies were conducted for a single curvature ratio equal to 0.05 at a constant Reynolds number equal to 40,000 for non-dimensional jet-to-target distances, L/d equal to 2, 4, 6, 8 and 10. Two non-dimensional jet-to-jet spacings, S/d, equal to 4 and 8 were studied. The effectiveness distribution for multiple jet impingement was noticed to be different from that for a single jet impingement. The entrainment from the surrounding was mitigated for the inner jets by the outer jets. The interaction of adjacent walljets forms a 'barrier' against the percolation of entrained ambient from the outer jet region towards the inner region. The zone of walljet interaction and region near to the inner jets were therefore observed to result in high effectiveness values. The inclined impingement of the jet reduces the strength of interaction of the walljets on up and downhill sides and thereby reduces the 'barrier effect' against the entrainment of ambient, which causes similar variation of effectiveness for all the jets in a row at high inclinations.